This invention relates to an extrusion head for moldings to be used in the construction of window, door and the like frames, as well as to a molding produced thereby.
Currently known and marketed are moldings, or sectional members, for use in window, door and the like building frames, which are obtained by extruding a PVC blank.
To impart to the molding the required stiffness and mechanical strength, it is necessary to produce a molding which has comparatively high wall thickness dimensions, with the obvious consequence that a considerable amount of material must go in their construction.
In an attempt to solve the above problem, moldings for window and door frames have been introduced and are currently marketed which comprise a rigid outer PVC extrusion the hollow inside whereof is completely filled with a rigid PVC foam, which in addition to improving the mechanical strength of the molding, also serves the function of greatly improving the thermal insulation properties of the molding.
The latter solution, while improving the situation, has failed to prove consistently satisfactory because the amount of plastics material expended is considerably higher, and moreover, a serious problem is encountered during the extrusion process owing to the difficulty inherent to the extrusion of the molding inner core which, as mentioned, is of expanded or foamed PVC.